Delving Into The Theories of Formation of The Moon

What Forged The Moon?

The “Giant Impact” is the favored scientific hypothesis for the Moon formation. Supporting evidence is the Earth’s spin and Moon’s orbit having same orientations.

Giant collisions are in-line with leading theories of the formation of the solar system.

Models suggested several satellite-sized bodies had formed colliding, or were captured by planets. Its’ possible Earth’s gravity snagged a passing body, just as Mars obtained the moons of Phobos and Deimos.

GRAIL was designed to study the Moon’s interior by looking for anomalies in its gravitational field caused by variations in its topography and the density of its rocks. Such anomalies alter the orbits of satellites, and the instruments on board Ebb and Flow were exquisitely sensitive to them. Using onboard rocket motors to vary both the distance between the probes and their altitude above the surface (which was 55km when mapping started, and was then gradually brought down to as low as 2km), the mission’s controllers were able to tease out fine detail unavailable from previous lunar satellites.

‘Big Splash’ Possible Option

The “Impact Hypothesis,” or “Big Splash,” says the Moon was formed by debris from a partial collision between the Earth and a planetoid the size of Mars, ~4.5 Billion Years Ago, bya, in the Hadean eon. This was 20-100 million years after the solar system coalesced.

According to modern theories of planet formation, Theia was part of Mars-sized bodies existing in the solar system 4.5 billion years ago. In this theory, the Earth had myriads of collisions with planet-sized bodies.

This earth-orbiting material coalesced into the Moon (month-century). Orbiting materials then stayed in stable Kepler orbits.

Regardless of the tilt of the Earth’s rotation before the impact, the earth’s equator and Moon’s orbit would have become co-planar in the aftermath of the impact.

In 2014, a German team reported Apollo samples had a slightly different isotopic signature from Earth rocks, which is statistically significant.

Theories abound. We know about compositional inconsistencies with Earth itself. Several inconsistencies with the “giant impact” hypothesis, include the Moon being enriched in siderophilic elements. Siderophile (from sideron, “iron,” and philia, “love”) elements are the transition metals, usually sinking into the core because they dissolve readily in iron whether solid or molten. Siderophile elements include gold, cobalt, iron, iridium, manganese, molybdenum, nickel, osmium, palladium, platinum, rhenium, rhodium and ruthenium.

Theories Galore

Another theory states Earth stole a moon from Venus.

If an ‘impactor’ was involved in a collision, it was roughly 10 percent Earth’s mass-the size of Mars.

The Moon’s iron oxide, FeO, content is 13 percent, and between Mars (18 percent) and the earth’s mantle (8 percent). This eliminates most of the proto-lunar material from the Earth’s mantle.

Recent research by NASA’s Lunar Science Institute, NLSI, hypothesizes Earth and Moon were created in a collision of two large planetary bodies.

But with no weather on the Moon, craters could have not eroded. For typical planets with a mass of 0.5-1 Earth masses, other-body impacts usually result in a single moon containing 4 percent of the ramming planet’s mass.

The Moon is also slowing Earth’s rotation by tidal braking, adding about 2 milliseconds/century. The energy Earth loses is absorbed by the moon, increasing its distance from Earth by 1.5 inches annually.

Apollo’s Moon Rocks

Analysis of lunar rocks brought back by Apollo astronauts show traces of the “planet” Theia (Journal Science).

One can study moon pictures with colors indicating both lunar topography, and gravitational sources.

Variations in the lunar gravity field were measured by NASA’s Gravity Recovery and Interior Laboratory, GRAIL, during the primary mapping mission in 2012. Very precise microwave measurements between two spacecraft, Ebb and Flow, mapped gravity exactly.

The “gal” does not mean gallon, but is named after Galileo Galilei, a physicist who made the first measurements of the Earth’s gravity. The unit “mGal” is used to measure gravity in NASA’s recent moon color chart.

We know meteorite bombardment went undisturbed for millions of years on the moon. In 2011, NASA’s Lunar Reconnaissance Orbiter, LRO, sent back a highly detailed moon map.

On that map, all acquired gravitational sources are highly variable, considering impacted meteorites.

With a moon having no weather for millions of years, buried meteorites could literally be a treasure-trove of something Earth does not have.

From the gravitational source map from GRAIL, there could be a buried meteorite containing mass amounts of gold, platinum, rhodium, or a host of other precious metals.

With certainty, those who visited the moon can say they looked back at time itself-perhaps eons worth, or possibly even several million years.

NASA Overturns Criticism

NASA refers to the rocks collected from the Moon as evidence of legitimacy. They knew the rocks could not have been formed under conditions on earth.

Analyses by scientists worldwide all agree the rocks originally came from the Moon.

Apollo samples are very distinguishable from both meteorites and Earth rocks, as they show lack of hydrous alteration products. There’s also evidence of impact events on an airless body, together with unique geo-chemical traits. Also, most are older than 200 million years-older than the oldest Earth rocks known.

How many realize one can look back in time millions of years just by a look in the nighttime sky?

A former Chemical Engineer, Kevin Roeten enjoys riding the third rail of journalism: politics and religion. He is a Guest Columnist for the Asheville Citizen-Times, and the Independent (Ohio), writes for numerous blogs, is an amateur astronomer, and delves into scientific topics.